Our overall research objective is to provide a family of nucleotide analogs which can be utilized as general reagents for studying the detailed structure of polynucleotides and (poly) nucleotide-protein complexes. Two approaches are being taken. 1) We are synthesizing photo sensitive nucleotide analogs and testing their ability to act as photo-affinity probes for analyzing the nucleotide binding sites of proteins. E. coli RNA polymerase and the ATP'ases of human erythrocyte membrane ghosts are the test system proteins. 2) We are utilizing covalent mercuri nucleotide 5'-triphosphates, and nucleotidyl transferase enzymes. Conditions have been found whereby DNA and RNA polymers can be directly mercurated. Since the introduction of the mercury substituent does not significantly alter polynucleotide structure we are planning to do the following, a) Prepare mercury derivatives of tRNA for crystallographic structure analysis, b) To develop a method of gene isolation based on hybridization of mercurated RNA followed by selective retension of hybrid material on columns of sulfhydryl-Sepharose, c) To develop a method of gene mapping in the electron microscope based on the ability of mercurated polynucleotides to complex with ferritin or other electron dense marker reagents.